The present invention relates to a suspension device of an agricultural machine with the features of the independent claim 1.
Such suspension devices or, as the case may be, agricultural machines with such suspension devices, are known from EP 1 060 649 B1 or from EP 1 880 590 A1, for example. In these devices known from the prior art, various tillage implements and sowing implements are attached to pivot arms such that the result is a suitable implement arrangement for the respectively intended use. The pivot arms are pivotably mounted on so-called flange tubes, and they have bearing sections, which surround the flange tube, with elastic bearing elements or squeeze bearing elements or rubber elements being arranged in each case between the mentioned bearing sections and the sections of the flange tube surrounded thereby.
The bearing sections of the pivot arms together with the flange tube accommodated therein as a rule have a square contour, and in their initial position they are rotated by approximately 45 degrees relative to each other, resulting in four triangle-shaped reception chambers for one bearing element each. Other combinations of flange tube and bearing section, such as for instance triangle-shaped contours, are, however, also possible and known.
One problem with such suspension devices frequently lies in stabilizing them and in the guidance between the bearing sections and the flange tube. An asymmetric arrangement of the tillage implements or the sowing implements at the pivot arm, such as for example, an inclined position of the coulter disks in relation to the driving direction or in relation to a perpendicular plane thereto, will cause transverse and lateral forces to build up, which partly become so great as to lead to substantial tilting moments, which in turn result in laterally tilting or twisting of the suspension devices or the pivot arms, as the case may be. By this tilting or by this inclined position, as the case may be, the pivot arm will moreover tend to shift transversely to the driving direction or along the flange tube parallelly thereto, as the case may be. Furthermore, the elastic bearing elements tend to become dislocated from the bearing sections.
EP 1 880 590 A1 already proposes a solution for solving the above-mentioned problems. For this purpose, the elastic bearing elements do not have the usual cylindrical design, but are rather designed to have a truncated cone form, at least partly and, in particular, at their end sections. This results in greater preload forces in the respective end sections of the bearing section, which is intended to lead not only to an improved lateral support, but also to prevent a dislocation of the bearing elements. A disadvantage of such a design, however, is that while the lateral support is improved, the possibility of twisting still remains. It is also possible that the force for the lateral support is insufficient due to the material quality of the bearing elements. This can be counteracted by increasing the material quality or the material hardness, leading, however, in turn to the risk that the preload forces become too great so that it can no longer be ensured that the suspension device can perform a sufficient pivoting motion in relation to the flange tube.
Disclosed in EP 1 541 003 A1 is moreover an overload protection, in particular for a soil working implement, with an elastic bearing, which consists of elastic bearing elements and two bearing shells, and, attached to the lower bearing shell, a shaft with a disk for tilling. In an unmounted state, the elastic bearing elements have an essentially round cross section with at least one longitudinally flattened portion. This flattened portion is intended to improve the elastic material characteristics of the bearing elements; the lateral support is likewise intended to be improved by such a design of the bearing elements.
DE 10 2009 058 342 A1 discloses a suspension device of an agricultural machine, which suspension device is particularly suited for tillage implements. The device comprises at least a pivot part carrying the machine part and a pivot part carrier, on which the pivot part is pivotably mounted. With a bearing section, the pivot part can surround the pivot part carrier in such a manner that bearing chambers are formed between the bearing section of the pivot part and the pivot part carrier. Elastic bearing elements can be associated with the bearing chambers, which bearing elements undergo an at least partial elastic deformation when the pivot part is pivoted. This known suspension, however, has the disadvantage that the forces of the lateral support depend on the material quality or on the Shore hardness of the bearing elements. This means that although a greater Shore hardness could improve the lateral support, this would, however, in this instance lead to decreasing the pivoting possibilities because greater preload forces also go along with a greater Shore hardness.
Also known are suspension devices, in which the flange tube and the inner surface of the bearing shells have the same cross section such that the inner surface of the bearing shell can pivot radially about the flange tube and is thus laterally supported. The suspension device in such a design, however, can also shift axially; and in addition, the dimensions of the flange tube and of the bearing shells must be adhered to very precisely, making this a very elaborate and costly approach.